Michael has a wide range of public health research interests, with a particular focus on environmental health, infectious diseases, and housing. He has published more than 250 peer-reviewed papers on these topics.

In 2013 Michael was awarded the HRC Liley Medal for his contribution to the health and medical sciences. In 2014 he was a recipient of the Prime Minister’s Science Prize as a member of He Kainga Oranga/Housing and Health Research Programme. In 2015 he was the NZ-UK Link Foundation Visiting Professor at the School of Advanced Study (SAS), University of London.